Okay, let's talk about structure. Writers, be they in the self publishing industry or otherwise, work in many different ways, and no way is right or wrong as it all depends on the individual concerned. For example, some writers prefer to plan before writing. They will have worked out every detail of the plot, every character's journey, possibly even the length of each and every chapter in the book before they even so much as write the first word.
Other writers may find this approach uncomfortable and binding (as do I, to be honest - in my mind, if you've already worked out absolutely every beat of the story in your mind beforehand, the writing itself becomes little more than transcribing, and seems like such a dull process I often then abandon it altogether!). They prefer to write in a looser fashion, sometimes so loose that the more organised writer might well throw up their hands in horror at the very idea.
Some writers even begin a novel with little idea of where it is going and only discover what the story is really about en route during the writing process. Each approach is not for everyone and discovering which approach - or some kind of happy medium in between those extremes - is an important part of developing your own writing 'voice'.
p.s. Discovering the best way to structure your writing is an important part of learning to be your own person as a writer.